I've read the webnovels during the pandemic, and the story has changed so much. This whole Kagura arc wasn't there before. Iirc, after the shogi tournament, there was a skirmish on his village and he used his powers to tunnel and collapse the mountain road just to protect his slow life.
to those complaining why isekai MCs with OP abilities like to hide their abilities and stuff, it's a Japanese thing. I've read the novels though and he ceased to be a background character after the saint arc.
Also, i think it was never stated in the manga, otome game developer is famous for...